How do I perform an unsigned right shift (>>> in Java) in C/C++?

In C, to get an unsigned shift, you just do a shift on an unsigned type.

unsigned int result = (unsigned int)valueToBeShifted >> shiftAmount;

Note that there is no guarantee that >> on a signed type gives you a signed shift in C — this is implementation defined behavior. Most common implementations produce a signed shift if the type is signed, however.